Adjustable bolster swing legs for reorienting crawlers for slipform paving machines

ABSTRACT

A paving machine for spreading, leveling and finishing concrete having a main frame, center module, bolsters laterally movably, and a crawler track associated with respective aft and forward ends of the bolsters. A bolster swing leg for each crawler track supports an upright jacking column. A worm gear drive permits rotational movements of the crawler track and the jacking column. A hinge bracket is interposed between each swing leg and a surface of the bolsters to enable pivotal movements of the swing leg. A length-adjustable holder engages the pivot pin on the hinge bracket and pivotally engages the swing leg. The holder permits pivotal motions of the swing leg in its length-adjustable configuration and prevents substantially any motion of the swing leg in its fixed-length configuration. A feedback loop cooperates with transducers keeping the crawler tracks position. The paving machine can be reconfigured into a narrowed transport configuration.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/897,125, filed on May 17, 2013; which is a continuation of U.S.application Ser. No. 13/069,096, filed on Mar. 22, 2011, now U.S. Pat.No. 8,459,898, issued Jun. 11, 2013; which claims the priority of U.S.Provisional Application No. 61/318,223, filed on Mar. 26, 2010, thedisclosures of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention concerns concrete slipform paving machines thathave a propelling unit or tractor from which a paving kit is suspendedwith which a layer of concrete is shaped and finished over theunderlying ground as the tractor travels along a road or airfieldalignment. The tractor of a concrete slipform paver has a rectilinearframe which straddles the concrete roadway or airfield pavement sectionthat is being paved. The frame is propelled and supported on either endby crawler tracks mounted on side bolsters. These side bolsters eachtypically have two hydraulic supporting jacking columns, each of whichconnects to a crawler track, that allow the tractor frame elevation tobe manually or automatically varied relative to the ground. The frame,and in particular a center module thereof, supports a dieselengine-driven hydraulic power unit which supplies power to the tractorand the paving kit.

The paving kit is conventionally suspended below the tractor frame bymechanical means, such as with hooks and a locking mechanism. The pavingkit takes its hydraulic power from the power unit on the tractor. Thetractor and the paving kit pass over fresh concrete placed in anddistributed over its path as a relatively even and level mass that canbe conveniently slipform-paved. During this process, thetractor-attached paving kit spreads the semi-solid concrete dumped inthe path of the paver, levels and vibrates it into a semi-liquid state,then confines and finishes the concrete back into a semi-solid slab withan upwardly exposed and finished surface. The sideforms mounted on eachside of the slipform paving kit shape and confine the sides of the slabduring the slipform paving process. Other kits can be attached to thesetractors such as kits for conveying and spreading concrete and trimmingand spreading base materials.

The tractor normally has four crawler tracks, but can also have onlythree, each mounted to a jacking column, supporting and propelling theframe during use of the paver in the paving direction. The jackingcolumns are carried on the bolsters, or on bolster swing legs connectedto the fore and aft ends of the side bolsters, that are pivotable aboutvertical axes to change the relative position of the crawlers for avariety of reasons and/or for changing the movement correction of thecrawlers and therewith of the paving machine during use. The bolsterswing legs with jacking columns and crawlers can also be relocated andmounted directly to the front and rear of the tractor center module, tothe outside of the side bolsters or directly to the outside of thetractor center module in some less conventional paving applications. Forthe purposes of this description, the focus is on the manner in whichbolster swing arms and the orientation of the crawlers can be changedand controlled in the more conventional paving configuration of themachine.

As is well known, tractor frames for slipform paving machines, whichtypically are extendable/retractable in the lateral direction to changethe widths of the tractor frame and the remainder of the paving machine,have a generally rectangularly shaped center module or platform whichsupports, for example, the power unit including the engine for thepaver, an operator platform, and the like. A side bolster is laterallymovable and secured to each lateral side of the tractor frame (by meansof male support tubes that telescopic in and out of the tractor centermodule), and bolster swing legs pivotally connect the fore and aft endsof the bolster to the respective jacking columns and crawlers of thepaver. The swing legs are pivotally mounted to front and aft ends of thebolsters on vertically oriented hinge pins so that pivotal movement ofthe swing legs moves their end portions, which mount the jacking columnand the crawlers, sideways relative to the paving direction of thepaving machine and in a generally horizontal plane for increasing ordecreasing the distance between the crawlers, and the distance andorientation of the crawlers relative to the tractor frame of the pavingmachine. Once the bolster swing legs supporting the jacking column withcrawler track have the desired spacing between them and the desiredorientation relative to the tractor frame, they are locked in place toprevent the crawler tracks from deviating from the desireddirection/position and to absorb any existing tolerances between thebolster ends and the bolster swing legs which, if permitted to exist,allow undesired orientational deviations of the crawlers. In the past,turnbuckles and/or hydraulic cylinders were employed to prevent suchtolerance-based play. To eliminate all play, two counteractingturnbuckle and/or hydraulic actuators arrangements were sometimesemployed to establish a positive, immovably locked position andorientation for each crawler track.

The position fixing turnbuckles and/or hydraulic actuators were securedto mounting brackets that were bolted to a hole pattern in the front (oraft) facing surfaces of the tractor frame and the bolster swing legsand/or between the side bolster ends and the bolster swing legs. To beeffective, the turnbuckles/hydraulic actuators must have a substantialangular inclination relative to the bolster swing leg. If this angularinclination becomes too small, the turnbuckles/hydraulic actuators loseeffectiveness and rigidity, which, if permitted to occur, can lead toundesired deviations in the desired orientation of the crawler tracks,and if the inclination becomes too large, the distance between the pointof connection of the turnbuckles/hydraulic actuators to the tractorframe and to the bolster swing leg can exceed the effective length ofthe turnbuckle or hydraulic actuator.

Thus, in the past, when the machine width had to be changed by asignificant amount it became necessary to reposition theturnbuckle/hydraulic actuator mounting bracket along the length (in alateral direction that is perpendicular to the travel direction) of thetractor frame to maintain the angular inclination of theturnbuckle/hydraulic actuator within an acceptable range. This was atime-consuming task that required skilled workers and, therefore, wascostly. In addition, the time it takes to change the position of themounting bracket for the turnbuckle/hydraulic actuator is a downtime forthe machine during which it is out of use and cannot generate revenues.

Bolster swing legs are used so that the crawler tracks can be relativelyquickly relocated in relationship to the edge of the concrete pavementthat is being laid down from the normal straight-ahead position, forexample to avoid obstacles in the path of the crawler tracks or to makeroom that may be required to allow tie bars to pass the inside of therear crawlers and the like. One of the conventional ways of relocatingthe crawler track was to support the side bolster of the tractor, usingthe jacking column to hydraulically lift the crawler off the ground,then to use one or more turnbuckles (or one or more hydraulic actuators)to mechanically pivot the bolster swing leg with the jacking column andcrawler track and, once the desired position is reached, to hold itthere with a turnbuckle or steamboat ratchet (or actuator). If only oneturnbuckle is used in the normal position, which is the inboard side ofthe bolster swing leg, the swing leg is free to move due to theinevitable manufacturing and assembly clearances and tolerances in theturnbuckle connections. These clearances are undesirable because if theswing leg is allowed to pivot or tilt under varying loads, it canadversely affect steering and elevation control. Because of thisconnection play, opposing turnbuckle sets were at times employed, onebeing located in the inboard side and one or more turnbuckles beinglocated on the outboard side of the swing leg. In such an arrangement,after the crawler track is in the desired position, the opposingturnbuckles are tensioned (pulled) against each other to keep the swingleg from moving. This transfers all the clearance in the pin connectionsto one side of the hole, eliminating any possible movement in theconnection. The drawback of this approach is that the outboardturnbuckles increase the overall machine profile outside the edge ofconcrete and therefore require more room for the machine when pavingpast obstacles in tight confines. If the outboard turnbuckle angle isdecreased to decrease the machine profile, the effectiveness of theturnbuckles at this flat angle in holding the swing leg can decrease toalmost nil. Further, every time the crawler track is relocated, all theturnbuckles must be readjusted.

Attempts have been made to eliminate the need for the outboard opposingturnbuckles by adding a hydraulic cylinder/actuator between the tractorframe and the swing leg behind the turnbuckle on the inboard of the leg.The cylinder effectively pushes the pin connection clearances to theinside of the turnbuckle connection holes and eliminates the risk ofswing leg movement by keeping the hydraulic actuator pressurized.

The relocation of the bolster swing leg and crawler track inrelationship to the tractor frame is further adversely affected by theneed to relocate the turnbuckle connection on the tractor frame where itconnects to the bolsters to which the swing leg is attached. Theturnbuckle connection on the bolster swing leg side typically stays atthe same connection point. In the past, the turnbuckle connection to thetractor frame posed several problems. One such problem was when thetractor frame was telescoped narrower. At wider tractor widths, theturnbuckle connects to the outboard end of the support beam of thetractor frame with a turnbuckle bracket that is bolted to the malesupport beam (that telescopes in and out of the tractor center module)with two or more bolts; however, if the tractor frame is telescopednarrower, the bracket will eventually interfere with the tractor centermodule, which prevents the further narrowing of the tractor frame. Oncethis point is reached, the turnbuckle mounting bracket therefore had tobe unbolted from the male support beam and rebolted to the tractorcenter module. To maintain the optimum turnbuckle angle to the swing legso the turnbuckle is effective in holding the leg in the desiredposition, the turnbuckle bracket had to be relocated along the tractorcenter module repeatedly, which slowed down the machine width changeprocess during each change. The inboard turnbuckles can also interferewith other attachments required on the front and rear of the machine,such as a spreader plow that is mounted off the front of the tractorframe, which had to be disconnected and reconnected, which increasescosts further. Another problem was when the swing leg complete withjacking column and crawler track is relocated to the outside of the sidebolster or mounted directly to the tractor center module, in some pavingapplications there was no place to connect the bolster swing leg orturnbuckles (hydraulic actuators).

The relocation of the bolster swing legs and crawler track inrelationship to the tractor frame is further adversely affected by thesteering cylinders that typically were used on the jacking columns. Thesteering cylinders allow the crawler track angle to be changed inrelationship to the jacking column for manual or automatic steeringpurposes. In the past, the steering cylinders at times protruded to theoutside of the associated steering column. This is undesirable becauseit increases the outside width of the paving machine, which dictates andwill limit how close the machine can pave next to a building orobstruction, and the stroke of the steering cylinder dictates how farthe swing leg can be swung inboard or outboard. Amongst others, such ajacking column steering cylinder configuration does not allow thecrawler tracks to be rotated 90° from their normal operating orientationwithout the time-consuming repinning or repositioning of the steering,which is a drawback.

It is however highly advantageous to rotate the crawlers to such a 90°steering position (and being able to steer the crawler track in thatposition) from their normal position when readjusting the machine forpaving different widths, maneuvering the machine around the jobsite, orfor readying the machine for transport to a different paving site. Insuch an event, the swing legs with jacking columns and crawlers arepivoted relative to the tractor frame until the crawlers extend in thelateral direction (which is perpendicular to the normal pavingdirection) of the paving machine, which minimizes the width of thepaving machine so the gauge between the crawler tracks in the transportposition is narrow enough to walk the machine onto a trailer and for itstransportation over normal roads to a new site. This outboard 90°bolster swing leg orientation is not to be confused with rotating justthe crawler tracks in the 90° position using 90° steering.

Thus, when repositioning the crawler tracks of a paving machine inaccordance with conventional methods, the machine is initiallyappropriately supported so that a first one of the bolster swingleg-mounted crawler tracks can be lifted off the ground. The turnbuckleis then used to pivot the bolster swing leg until the jacking column andthe associated crawler are at the desired (lateral) position and havethe required crawler orientation. If the needed lateral movement of thecrawler is too great, the turnbuckle mounting bracket must berepositioned by unbolting it from the frame and rebolting it thereto ata hole pattern located at the appropriate (lateral) point on the tractorframe or the center module. Thereafter, the turnbuckle is tightened inthe new position of the crawler so that the bolster swing leg can nolonger move and the orientation of the crawler is maintained.Thereafter, the crawler is lowered to the ground, it is rotated aboutthe vertical axis of the jacking column to place it in the desiredorientation, and an orientation measuring transducer is reset for thenew crawler orientation to keep the crawler in the straight-aheadposition. This has to be repeated for each of the typically fourcrawlers of the paving machine, a process that is time-consuming, costlyand results in a prolonged, unproductive downtime for the machine. Thiscost is encountered each time the lateral position of the crawler and/orturnbuckle mounting bracket is changed and the crawlers must then bereoriented relative to the frame so that they face in the requiredtransport direction. This procedure is also used to ready the pavingmachine for transportation to a new work site. In such an event, theswing legs are pivoted relative to the frame until the crawlers extendin the lateral direction (which is perpendicular to the normal pavingdirection) of the paving machine, which minimizes the width of thepaving machine for transportation to a new site.

In an alternative approach used in the past, the crawlers and theassociated jacking columns were connected to the fore and aft ends ofthe side bolsters and fixed mounted to the end of the parallel linkagesand oriented so that the crawlers extend in the paving direction of thepaving machine. The parallel linkages typically include a hydraulicactuator to assist in the crawler track relocation and to hold thecrawler track in the desired position. This approach simplified thelateral adjustment of the positions/orientations of the crawlers inrelationship to the tractor as compared to crawlers mounted on pivotedswing legs because no matter where the crawler track was repositioned,the crawler track always remained oriented straight ahead and theturnbuckle relocation issue went away. However, in such arrangements,the limited range of movement of the parallel linkages with hydraulicactuator limits how narrowly the machine can be collapsed fortransporting it over highways (with standard highway width restrictions)to new construction sites. The ability to quickly and efficiently movethe paving machine from one site to the next, which is highly desirablefor the efficient use of the machine, is lost with this approach.Instead, paving machines employing such parallel linkages for thecrawlers required that the tractor frame itself had to be collapsed inorder to narrow the width of the machine sufficiently so that it couldbe transported over highways. This requires that either the paving kititself be telescopic or that the paving kit is removed from the tractor.In either case, this could significantly increase the overall cost ofthe machine or the cost or time required for moving the machine and istherefore an undesirable alternative. The only way to overcome thislimitation is to add a pivot hinge (with a means to lock/pin the pivothinge in either the working or transport position) between the sidebolster and the parallel linkage to allow the parallel linkage withjacking columns and crawlers to pivot outboard relative to the tractorframe until the crawlers extend in the lateral direction (which isperpendicular to the normal paving direction) of the paving machinerequired for loading on a trailer and transport. Of course, adding thepivot hinge with a pinning mechanism to each corner of the machine iscostly, and pinning and unpinning of the hinge is time-consuming.

BRIEF SUMMARY OF THE INVENTION

According to a first aspect of the present invention, each bolster swingleg is pivotally mounted on a hinge bracket that is secured to the front(or aft) ends of the side bolsters of the paving machine. This bracketalso supports the turnbuckle or, preferably, a hydraulic actuator whicheliminates the need to tie the swing leg into the tractor frame forholding the swing leg, and the crawler track secured to it, in a fixedposition during paving. One end of the turnbuckle or actuator is tiedinto the swing leg conventionally, while the other end is mounted to thehinge bracket. This eliminates the need encountered in the past torelocate the turnbuckle mounts on the tractor frame when the width ofthe tractor frame is changed. Instead, in accordance with the presentinvention, every time the width of the paving machine is changed, theattachment point for the turnbuckle or hydraulic actuator automaticallyfollows the positional change of the swing leg because the attachmentpoint is mounted on the hinge bracket, that is, in a fixed positionrelative to the bolster and the swing leg.

To facilitate the required realignment of the crawler tracks, anotherimportant aspect of the present invention preferably replaces theturnbuckles with hydraulic actuators and provides angular positiontransducers at the pivot connection for the swing leg at the hingebracket and another such transducer between the jacking column and thecrawler track. An onboard computer or other processor receives theoutputs from the transducers and generates a signal to pivot the crawlertrack relative to the associated jacking column to keep the crawlertracks oriented in the paving direction when the angular orientation ofthe swing leg changes, and also keeps all the crawler tracks'orientations synchronized. Thus, no matter what the swing leg angle is,the crawler track stays straight ahead in the paving direction andposition. Of course it is also possible to override this computerizedfeature so the crawler track orientation can be changed relative to thebolster swing leg, which may be required from time to time for widthchange, maneuvering on site, etc.

The bolster swing leg hydraulic actuator and the hydraulic rotary powerdrive or steering cylinder for pivoting the crawler track relative tothe jacking column working in cooperation with the position transducersallow the swing leg with crawler track to be held in a fixed location inrelationship to the edge of the concrete. A closed loop feedback systemthat connects the hydraulic actuator for the swing leg, the rotary powerdrive for the crawler, and the onboard computer always maintains theswing leg angle at a fixed, preset angle. If the swing leg migrates awayfrom a preset angle, the swing leg hydraulic cylinder is actuated tomaintain the preset angle and at the same time the necessary adjustmentsto the crawler track orientation are made with the hydraulic rotarypower drive or steering cylinder. Alternatively, a hydraulic systemusing a locking valve can be provided instead of the position transducerand feedback loop for holding the swing leg in the desired position.

Thus, the crawler track positions can be relocated when the machine iswalked forward or backward while the crawler tracks at all times stay intheir straight-ahead normal operating orientation and position withoutrequiring any manual mechanical or electronic adjustments. The crawlertracks can also be relocated when the machine is stationary bysupporting the weight of the machine off the ground, then hydraulicallylifting each crawler track (one at a time) off the ground, andthereafter using the swing leg hydraulic cylinder and positiontransducer working in conjunction with the power drive or steeringcylinder between the jacking column and the crawler track for moving thecrawler track to another position.

A still further aspect of the present invention eliminates the need toreposition the steering cylinder on the jacking columns when the crawlertrack is repositioned within the range of the swing leg cylinder and toallow 90° steering without having to reposition the steering cylinder byemploying a hydraulic motor driven rotary actuator (slew gear) with anangular position transducer as the power drive between the crawler trackand the jacking column. The rotary actuator also allows a wide range ofsteering angles while in the 90° steering mode to make the machinehighly maneuverable on site. Working in conjunction with the swing legposition transducer, and after unpinning the swing leg hydrauliccylinder from the swing leg, the rotary actuators allow the machine tobe preprogrammed to first turn the crawler tracks relative to thejacking columns normal to the paving direction, and then walk thecrawler tracks on the ground in an arc around the pivot shaft of theswing legs into their outboard transport position (in which the crawlersare oriented 90°, i.e. substantially transverse to the paving direction)so that the paving machine can be sufficiently narrowed for moving itover ordinary highways to a new paving site with a legal or otherwiseapproved transport width dimension, or, for maneuvering the pavingmachine around a paving site which is tightly confined. The heretoforecommon need to manually move the swing legs with jacking columns andcrawler tracks into the outboard position as previously described isthereby eliminated, which significantly reduces the time required toready the machine for transport and/or for maneuvering the machine atthe work site.

Thus, a paving machine constructed in accordance with the presentinvention has a main frame that includes a center module, a side bolsterthat is laterally movably connected to respective lateral sides of thecenter module for changing a spacing between the bolsters, a crawlertrack associated with respective aft and forward ends of the bolsters,and a bolster swing leg for each crawler track. An upright jackingcolumn is secured to the free end of the swing leg, and a connectionbetween the jacking column and the crawler track permits rotationalmovements of the crawler track and the jacking column about an uprightaxis. A hinge bracket is interposed between each swing leg and anassociated surface of the bolsters and includes a fixed, upright pivotshaft that pivotally engages the swing leg for pivotal movements in asubstantially horizontal plane. The hinge plate includes a pivot pinthat is laterally spaced from and fixed in relation to the pivot shaft.A length-adjustable, preferably hydraulically actuated, holder iscapable of being held at a fixed length and has a first end thatpivotally engages the pivot pin and a second end that pivotally engagesthe swing leg. The holder permits pivotal motions of the swing leg aboutthe hinge pin when in its length-adjustable configuration and preventssubstantially any motion of the swing leg when the holder is in itsfixed-length configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational, perspective view of a complete pavingmachine having pivotable swing legs with a jacking column and a crawler,each constructed in accordance with the present invention;

FIG. 2 is a partial, simplified plan view of portions of a pavingmachine illustrating the pivotal swing leg of the present invention;

FIG. 3 is a perspective, front elevational view of a hinge bracket forsecuring the swing leg to the paving machine;

FIG. 4 is a front elevational view, in section, taken through thevertical center line of the jacking column and crawler, which are onlyschematically shown in FIG. 1;

FIG. 4A is an enlargement of the portion of FIG. 4 within the circle A-Aof FIG. 4;

FIG. 5 is a front elevational view, in section, through the pivotconnection between the hinge bracket shown in FIG. 3 and the bolsterswing leg attached thereto with a pivot pin;

FIG. 6 is a schematic plan view similar to FIG. 2 and illustrates theattachment of the bolster swing legs to the aft portion of the pavingmachine, with the paving machine having an additional cross beam betweenthe tractor frame and the swing legs for additional kits that may bemounted on the paving machine;

FIG. 6A shows in plan view a paving machine with a DBI Moduleincorporating special bolt-in short bolster extensions with built-inmounts for DBI longitudinal support beams;

FIG. 6B is an illustration similar to FIG. 6A with the paving machineand the DBI shown in various relative positions as they are beingreadied for transportation while in their respective transportorientations;

FIG. 6C is a side elevation of the paving machine shown in FIG. 6B, inits transport orientation;

FIG. 7 is a perspective, side-elevational view showing the bolster swingleg that is pivotally secured to the hinge bracket; and

FIGS. 8A-E are schematic plan views of the paving machine whichillustrate reconfiguring the machine into its transportation mode (orvice versa).

DETAILED DESCRIPTION OF THE INVENTION

Referring initially to FIG. 1, a concrete slipform paving machine 2 hasa main tractor frame 4 defined by a center module or platform 6 thatcarries the diesel engine powered power unit 8 of the paving machine andfrom which extendable or telescoping male support beams 10 extendoutwardly in a lateral direction. Side bolsters 12 are secured to therespective outboard ends of the support beams. Upright jacking columns14 are mounted in the vicinity of respective front and aft ends of thebolsters, and crawlers 16 are conventionally secured to the lower endsof the jacking columns. The jacking columns are hydraulically poweredfor raising and lowering of the paving machine relative to the crawlerson the ground. The crawlers are mounted to the lower ends of the jackingcolumns, and they are rotatable relative to the jacking columns aboutvertical axes, an arrangement that is known in the art. The crawlerssupport the entire machine and move it over the ground.

The respective bolsters can be moved in the lateral direction relativeto the center module so that the machine frame, including the crawlers,straddles a paving kit (not separately shown) that extends over, clearsand forms a strip of concrete (not shown) being laid down by themachine. When finished, the strip of concrete defines an upwardlyexposed, appropriately leveled and finished concrete surface (not shown)that extends across the strip between the upright sides of the concretestrip.

In use, the paving machine is aligned with the paving direction 18 sothat the concrete strip can be laid between the crawlers 16 of themachine over a width determined by a paving kit 63 suspended from themain tractor frame. Fresh concrete is deposited in front of the machine,a spreader plow or a spreading auger (not shown) approximately levelsthe concrete over a major portion of the width of the concrete strip,and, as the machine advances forwardly, a metering gate substantiallyevenly spreads the top of the fresh concrete. Following the“liquification” of the concrete by vibrators supported by a vibratorrack at a fixed elevation on the front side of the paving kit, finishingpans (not shown in FIG. 1) are provided on the aft end of the paving kitto finish the top surface of the concrete as the paving kit passes overit, while sideform(s) form the sides of the concrete strip or slab. Afinished concrete strip emerges from the aft end of the paving machineand is permitted to conventionally set and harden.

Referring to FIGS. 1-5, each crawler 16 and the associated jackingcolumn 14 are mounted to a free end 19 (shown in FIG. 7) of a bolsterswing leg 20. The swing leg is typically formed as a box beam 22 and hasanother end 21 (shown in FIG. 7) that is pivotal about a verticallyoriented pivot shaft 24 which extends through a bearing bushing 26 thatis supported in its vertical orientation on a hinge bracket 28 withspaced-apart support webs 30.

The hinge bracket has appropriately positioned fastening holes 32 forsecuring it to respective end surfaces 34 of side bolsters 12 withconventional bolt and nut fasteners 23 as shown, for example, in FIG. 7.A female keyway is provided on the jacking column bolting flange 57(shown in FIG. 4) with male keyways provided on the mating boltingflanges to take the shear of the bolts and to eliminate possiblemisalignment.

The ends of box beams 22 adjacent bolster end surface 34 have connectorplates 36, secured to the top and bottom surfaces of the box beam bywelding, for example. The connector plates project towards the tractorframe past the end of the box beam and have holes that pivotally engagepivot shaft 24 in bearing bushing 26 of the hinge bracket so that theswing legs are free to pivot relative to bolsters 12 in a horizontalplane (as indicated in FIG. 2) about an upright axis defined by thepivot shaft.

The closed end of the cylinder of a hydraulic actuator 38 is pivotallypinned to two spaced-apart support plates which are secured, e.g.welded, to the inside of the hinge bracket 28 and a mid-portion ofbearing bushing 26, as is best seen in FIG. 3. The support platesinclude aligned bores 42 that are laterally spaced some distance awayfrom the bearing bushing 26. The closed end of the hydraulic cylinder ispivotally movably secured to the support plates with a pin that extendsthrough the bores. The piston 44 of the hydraulic actuator is pivotallypinned to a pair of spaced-apart brackets 46 which are located betweenthe ends of the swing leg and typically relatively closer to its freeend 19. When the hydraulic actuator is pinned to the hinge bracket 28and the brackets on bolster swing leg 20, it is angularly inclinedrelative to the paving direction 18, as best seen in FIGS. 1 and 2. Itis foreseen that on a larger machine more than one, e.g. two, verticallyspaced-apart hydraulic cylinders placed above each other may be requiredto generate the force required to hold the bolster swing leg in a fixedposition relative to the male pivot hinge. Further, if desired, forexample for cost reasons, hydraulic actuators can be replaced byturnbuckles.

When assembled installed between hinge bracket 28 and swing leg 20,hydraulic actuator 38 can be energized to pivot bolster swing leg 20 ina horizontal plane as schematically illustrated in FIG. 2. Since hingebracket 28 is secured to end face 34 of bolster 12, the angularinclination of the actuator relative to the bolster swing leg does notchange when the length of the tractor frame 4 (in the lateral directionperpendicular to the normal paving direction 18) is changed. There istherefore no need to reposition the hinge bracket that secures one endof the hydraulic actuator to the machine frame, as was necessary in thepast. The extendable length of the hydraulic actuator and its attachmentpoints to hinge bracket 28 and swing leg 20 are chosen so that theangular inclination of the hydraulic actuator relative to the bolsterswing leg is maintained over a reasonably large arc (as schematicallyillustrated in FIG. 2) that is sufficient to permit repositioning of theswing leg during normal use encountering normal operating conditions ofthe paving machine without having to disconnect the actuator from theswing leg and/or the hinge bracket.

However, when the swing legs are to be rotated 90° from the pavingdirection 18 towards a position that is laterally outward of bolsters12, principally for readying the paving machine so that it can betransported by truck and trailer to a new location, hydraulic actuator38 is disengaged from at least one of the swing leg or the hinge bracket28, for example by pulling pin 41 that connects the end of piston 44 tobrackets 46 on the swing leg, to prevent interference between thehydraulic actuator and support plates 40 and/or bearing bushing 26 ofthe hinge bracket.

When bolster swing legs 20 are longitudinally aligned with tractor frame4 and its laterally extending support beams 10, a position in which thelegs are oriented approximately perpendicular to paving direction 18, itis preferred to pin the swing legs in that position during shipment ofthe paving machine with a turnbuckle or other fastener (not shown) towebs 45, 47 on the laterally facing surfaces of the bolster and theswing leg as seen in FIG. 2. The turnbuckle or the like is released atthe new location so that the swing legs can be returned to their normaloperating position in which they are parallel, or only slightlyangularly inclined relative to the paving direction 18.

Each time the bolster swing legs 20 are pivoted inwardly or outwardlyrelative to tractor frame 4 of the paving machine, the relative angularinclination between the bolster swing legs and the tractor framechanges. This change is replicated by crawler tracks 16 mounted belowjacking columns 14 at the free end of the swing legs. This change incrawler track orientation has to be compensated for so that, followingthe pivotal movement of the swing leg, and preferably simultaneouslytherewith in real time, the crawler tracks extend in the pavingdirection. This is done by adjusting the angular orientation of thecrawler track by an amount that depends on or is a function of theangular displacement of the swing legs relative to the hinge bracket 28so that the crawler tracks always remain in alignment with pavingdirection 18 of the paving machine, as is schematically illustrated inFIG. 2 by the parallel orientation of the crawler tracks (in part shownin phantom lines in FIG. 2) irrespective of the angular orientation ofthe swing legs. This relocation process can be accomplished while themachine is supported so the crawler track can be lifted off the groundand relocated to the desired location inwardly or outwardly. With thisrelocation process, typically each swing leg/crawler track is relocatedone at a time. Alternatively, this relocation process can also beaccomplished while the machine is walking forward or backward. Forexample, for moving outwards, the angle of the crawler can behydraulically “jogged” slightly outward while walking the swingleg/crawler track to the desired location with or without the assistanceof the swing leg hydraulic cylinder. Once the desired position isreached and the job switch disengaged, the crawler track willautomatically go back to the straight-ahead position. In the alternatecase, the crawler track relocation process is done while walking in theforward or reverse direction moving one swing leg/crawler track at atime or moving more or all four at a time.

Referring to the drawings, and particularly to FIGS. 4 and 7 thereof,jacking column 14 has telescoping outer and inner tubes 48, 50 of agenerally rectangular cross-section, as is typical for jacking columnson paving machines, and a vertically oriented hydraulic actuator 52having its cylinder and piston appropriately secured, e.g. by pinning,to the outer and inner tubes. Activation of the hydraulic actuatortelescopingly moves the outer and inner tubes relative to each other forlengthening or shortening the distance between the crawler track and thebolster swing leg 20 for raising or lowering the paving machine relativeto the ground or, while the paving machine is otherwise supported,raising or lowering the crawler track off the ground. Spaced-apart axialbearings 54 keep the tubes aligned and permit them to slide relative toeach other in their axial direction while maintaining tight clearancesto minimize backlash. A support structure 57 is further provided forsecuring the jacking columns to free ends 19 of the bolster legs. Thisconstruction of jacking column 14 is conventional and is therefore notfurther described herein.

A slew or worm gear drive or other rotary actuator 60 is bolted to amounting plate 56 at the lower end of inner tube 50 of the jackingcolumn. The worm gear drive has a ring gear 58 that is driven by a pairof diametrically opposite, hydraulically activated helical worm drives61 carried on a ring-shaped member 63 disposed between an inner bearingrace 65 of the worm gear drives and a transverse portion 66 of yoke 62,to which the ring-shaped member is secured. An outer bearing race 67 issecured, e.g. bolted, to the lower end of mounting plate 56 at the endof inner tube 50. On its periphery, the outer bearing race 67 definesring gear 58. Such slew gear drives are commercially available fromKinematics Manufacturing, Inc., of 2221 W. Melinda Lane, Phoenix, Ariz.85027, as “Slewing Drive s17b-102m-200ra”. Providing the slew gear drivewith two oppositely arranged worm drives increases the power availableto rotate the crawler track while a portion of the total machine load iscarried by it. The slew drive design also effectively minimizesundesirable play or “backlash” during steering of the crawler track andeffectively minimizes undesirable play or backlash between the yoke 62and the jacking column 14 whether the slew gear drive is activated ordeactivated.

An angular position transducer or sensor 70 is arranged inside anupwardly open can 72 (provided to protect the sensor) that is disposedwithin an opening 69 in the transverse portion 66 of yoke 62. Supports74 extend across opening 69 and secure the can with transducer 70 at therotational center between the jacking column and the yoke. Thetransducer cooperates with a trigger pin 68 extending downwardly fromthe under side of plate 56 and a suitable actuator arm that turns thetransducer. Alternatively, the trigger pin can cooperate with thetransducer via a belt drive 64 as schematically indicated in FIG. 4A.

Transducer 70, in cooperation with trigger pin 68, generates a signalthat indicates the angular position of yoke 62 relative to jackingcolumn 14 and any changes in the angular position due to rotationalmovements of the yoke. Corresponding output signals are generated by thetransducer and fed to a lead 84 not shown in FIG. 4 but shown in FIG. 5.

Referring to the drawings, and in particular to FIGS. 5 and 7 thereof,another angular position transducer 78 is placed on top of swing legpivot shaft 24 (FIG. 5). As is best seen in FIG. 7, the top of the pivotshaft defines a generally drop-shaped head 86 that is engaged by blocks88 fixed to the upper side of connector plate 36 so that pivot shaft 24is rotationally fixed to the connector plate and duplicates the angularmovements of swing leg 20 about the pivot shaft. Replaceable bearingsare provided at the top and bottom of the male hinge bearing (shown inFIG. 3) as well as a means to get grease to them (not shown in thedrawings) so the pivot shaft 24 does not seize in the bearing, whichwould prevent the swing leg from freely rotating.

Angular position transducer 78 is mounted inside a downwardly openprotective can 90, as seen in FIG. 5, which is bolted to hinge bracket28 via an upright holding arm 92.

A trigger pin 94 projects upwardly from the top surface of pivot shaft24 and cooperates with angular position transducer 78 to generate anangular position signal which reflects the angular inclination betweenthe pivot shaft and the hinge bracket, and which changes when thebolster swing leg 20 changes its angular position relative to the hingebracket 28, and therewith also relative to bolster 12 and tractor frame4. The output of transducer 78 is fed to a lead 80.

The output signal of the position transducer 78 is fed via lead 80 to anonboard computer 82 of the paving machine, or another suitableprocessor, which receives as its second input the output signal ofposition transducer 70 between jacking column 14 and crawler tracks 16via a lead 84, as is schematically illustrated in FIG. 5.

Onboard computer or processor 82 and the associated transducers 70, 78form a feedback loop in which the computer receives the angular positionsignal from swing leg transducer 78. When the angular position of theswing leg changes, the output signal from transducer 78 changescorrespondingly. As a result of this orientational change of the swingleg, the angular orientation of the crawler tracks becomes angularlyinclined relative to paving direction 18. Computer 82 calculates by howmuch the angle of the crawler track has to be changed relative to thejacking column (which has also been angularly offset relative to thetransport direction by the swivel motion of the swing leg) to reset thecrawler track suspended from yoke 62 to the angular orientation of thedesired paving direction. The onboard computer then signals by how muchworm gear drive 60 must rotationally adjust the orientation of yoke 62and crawler tracks 16 to again align the crawler tracks with the pavingdirection. This process is repeated each time the angular position ofthe swing leg is changed, or when for other reasons the angularorientation of the crawler tracks becomes misaligned from the desiredpaving direction of the machine.

Thus, the above-described feedback loop automatically adjusts theangular orientation of the crawler tracks so that the tracks remainoriented in the travel direction without any need to stop operation ofthe machine or manually adjust the orientation of the tracks and/or theswing legs.

FIGS. 8A-E illustrate with more particularity how the paving machine ofthe present invention is readily, quickly and inexpensively reconfiguredbetween its paving orientation shown in FIG. 8A or configuration forlaying down the layer of concrete, and its transportation orientationshown in FIG. 8E or configuration in which the width of the machine isreduced to a roadway accepted width with minimal efforts.

As already mentioned, from time to time the paving machine must bereoriented, either at the work site for maneuvering or repositioning itaround, or to ready the machine for transport to a different site, whichrequires loading the machine on a suitable trailer (not shown) and thenhauling it to the new site over available roads.

Maneuvering the paving machine around the work site is accomplished byrotating the crawlers 16 relative to the jacking column 14 and then, orsimultaneously therewith, activating the crawlers to move the machineinto the desired position or to a given location at the site.

For loading the paving machine for transport to a different site on atrailer over standard highways, it is necessary to reduce the transportwidth of the paving machine to the maximum allowable width for highwayvehicles. With the crawlers resting on the ground and initially facingin the paving direction 18, they are rotated 90° about the verticaljacking column axis with worm gear drive 60 into a position in whichthey are substantially transverse to the paving direction. Therespective hydraulic actuators 38 keep the associated swing legs 20 intheir paving orientation as seen in FIG. 8B. The ends of the hydraulicactuators 38 are then disconnected from the associated swing legs 20 byremoving a pin, then with the crawler track on the ground, walking in anarc around the pivot shaft of the swing leg as shown in FIG. 8C. Once inthis position, the crawlers are again rotated 90° about the verticaljacking column axis with worm gear drive 60 to place the swing legs intheir transport orientation (shown in FIG. 8D) which is perpendicular tothe paving direction. Finally, a turnbuckle 95 or like holding device isapplied to the main frame side bolster of the paving machine and theswing legs to fix the latter in their transport orientation. Thisprocess is repeated at each corner of the machine until each swing legand crawler track is in the transport orientation and the swing legs arein their transport orientation (FIG. 8E) and perpendicular to the pavingdirection (FIG. 8D).

With the earlier described, cooperating position transducers 70, angulartransducer 78 (not shown in FIGS. 8A-E) and worm gear drive 60, or ifdesired manually, the crawlers 16 are thereby brought into alignmentwith the bolster swing legs, which, in the transport direction, areoriented perpendicular to the paving direction 18 and do not materiallyextend laterally past the remainder of the paving machine, so that theentire machine width is within permissible width limits for highwaytransportation. Once the crawler and the associated swing leg 20 are intheir transport orientation, which preferably is slightly more than 90°,e.g. 95°, the tightened transportation turnbuckle 95 having its endsattached to the paving machine frame side bolster and the swing armprevents movements of the swing leg and the crawler out of theirtransport orientation while the paving machine is moved to another site.

Thus, in the transport position the swing legs and crawlers are parallelto and extend past the respective lateral ends of the paving machinewhile the overall width is kept within width limits allowed for highwayvehicles.

Placing the paving machine in the transport direction requires littletime since the operation can be quickly performed and the crawlers canthen be used to move the paving machine onto a trailer for transport toa different site without requiring heavy lifting equipment such as acrane to place the paving machine from the paving to the transportdirections, and vice versa.

FIG. 6 shows a paving machine 2 including a center module 6, laterallyextending support beams 10, side bolsters 12, jacking columns 14 andcrawlers 16 as described above. The paving machine can be used, forexample, with a dowel bar inserter 116 for intermittently insertingdowel bars (not shown) into the freshly laid down concrete stripimmediately behind the paving kit. Such a dowel bar inserter, itsconstruction and attachment to the paving machine are described, forexample, in commonly owned, copending U.S. patent application Ser. No.12/556,486, filed Sep. 9, 2009, for a Paver Having Dowel Bar InserterWith Automated Dowel Bar Feeder, the disclosure of which is incorporatedherein by reference as if it were fully set forth herein.

To movably support the dowel bar inserter 116, for example, or anotherkit of the paving machine from the tractor frame, the lateral ends 112of a cross beam 110 are tied into, that is, they are typically boltedto, rearwardly extending bolster extensions 114. The longitudinalsupport beams 43 for the dowel bar inserter shown (the rest of the dowelbar inserter is not shown) attach to the rear of the tractor frame bymeans of a mounting bracket attached to the support beam in the frontand to the rear cross beam 110 in the rear. The forward ends of thebolster extensions 114 are secured to the rearwardly facing end surfacesof the main tractor frame bolsters 12 that can be provided with orwithout an additional bolt-in hinge 102. When no hinge in the bolster isprovided, the bolster extension 114 must be removed prior totransporting the machine. Prior to removing the bolster extensions forloading and transporting the paver, the rear hinge 36 and swing leg 20along with the jacking column 14 and crawler track 16 (the entireassembly) must be removed and then lifted and bolted to the rear of themain frame side bolster 12 and the paver put into the transportorientation. The weight of this entire swing leg, jacking column andcrawler track assembly can be handled with a relatively small crane.When the bolster extension is provided with a bolt-in hinge 102, thebolster extension 114, swing leg, jacking column and crawler track canbe left on the paving machine so that by hinging the bolsters into theoutboard transport position, the paving machine is capable ofself-loading onto a trailer, with the bolster, swing leg and jackingcolumn with crawler track folded up for transport. The advantage of thisis that no crane is required to remove the bolster extension in order totransport.

A variation to the DBI mounting arrangement shown in FIG. 6 with abolt-in hinge is the mounting arrangement shown in FIGS. 6A and 6B.Instead of a bolt-in hinge 102, a special bolt-in short bolsterextension 104 with built-in mount 106 for the DBI longitudinal supportbeam 43 is supplied. Instead of the longitudinal support beams 43attaching to the rear of the tractor frame by means of a mountingbracket described above, the longitudinal support beams mount to thebolster extension 104. When the bolster extension is provided with aspecial bolt-in short bolster extension 104 with built-in mount 106 forthe DBI longitudinal support beam, a practical and fastloading/transport solution is possible for both the paver and the DBI,providing a medium-size crane is readily available. Because the bolsterextensions are tied to the DBI supporting longitudinal support beam 43in this configuration and also to the rear cross beam 110, a rectilinearframe is formed where the DBI, complete with bolster extensions 114 and104, becomes a kit (module) 108 of a legally transportable width. Ifthis DBI Module is supported complete with bolter extensions 114 and104, while it is still attached to the paver, the rear hinge 36 andswing leg 20 along with the jacking column and crawler track (the entireassembly), it can be lifted with a relatively light small crane (withoutdisconnecting any of the hydraulic or electrical connections) and boltedto the side of the main frame side bolster 12, using the universalbolting pattern found on the side bolster 12 as shown in FIGS. 6B and 6C(that matches the hole pattern of the swing leg) covered and describedin copending, commonly owned U.S. patent application Ser. No.12/703,101, filed Feb. 9, 2010, for a Slipform Paving Machine WithAdjustable Length Tractor Frame. This swing leg, jacking column andcrawler track assembly is mounted in the transport orientation as shownin FIG. 6B and FIG. 6C. Once this procedure is completed on the oppositeside of the machine, the complete DBI with bolster extensions 114 and104 and the DBI Module 108 can be lifted as a module 108 on a trucktransporting trailer. With the DBI Module 108 removed from the rear ofthe paver tractor frame, then the other front swing leg and jackingcolumn with crawler track can be walked into the transport orientationas described herein. With all the swing legs and jacking columns withcrawler tracks now in the transport orientation, the paver can self-loadby walking onto a transporting trailer. The advantage of thisarrangement is that if a medium-size crane is available, adding orremoving the DBI Module 108 and unloading or loading the DBI Module andpaver can be done very rapidly.

FIG. 6B schematically illustrates the paving machine and the DBI Modulearranged for transport in two loads, as a crawler track paver module andas a DBI Module 108. The right and left rear jacking columns 14/crawler16/swing leg 20/rear hinge 36 subassembly has been moved into itstransport orientation as previously described. The left front jackingcolumn/crawler/swing leg/rear hinge subassembly has been rotated towardsits transport orientation, while the right front jacking column,crawler/swing leg/front hinge subassembly is shown in its pavingorientation and must still be rotated into its transport orientationbefore the modules are ready for loading onto a trailer (not shown).

Cross beam 110 may comprise a non-telescoping or a telescoping crossbeam, laterally extendable and retractable support system that has afemale center housing 6′ which movably receives male support beams 10′that extend in opposite directions from the center housing towards therearward bolster extensions 76. The construction and operation oftelescoping cross beam 110 and the kits, such as a dowel bar inserterkit suspended therefrom, are described in copending, commonly owned U.S.patent application Ser. No. 12/703,101, filed Feb. 9, 2010, for aSlipform Paving Machine With Adjustable Length Tractor Frame, thedisclosure of which is incorporated herein by reference.

What is claimed is:
 1. A paving machine configured to move in a pavingdirection for spreading, leveling and finishing concrete into a formhaving a generally upwardly exposed, finished concrete surface andterminating in lateral concrete sides, the paving machine comprising: acenter module having a forward end, an aft end, and lateral sides; atleast two forward bolsters laterally and movably connected to respectivelateral sides of the center module; at least two aft bolsters laterallyand movably connected to respective lateral sides of the center module;a crawler track mechanically coupled to each forward bolster and eachaft bolster; a swing leg for each bolster; an upright jacking columnsecured to each swing leg, having a rotary connection between thejacking column and the crawler track permitting relative rotationalmovements of the crawler track with regard to the jacking column aboutan upright axis; and a power drive unit between associated jackingcolumns and crawler tracks configured for translating relativerotational movements between the associated jacking columns and thecrawler tracks.
 2. A paving machine according to claim 1 furthercomprising: a first angular position transducer between associatedjacking columns and crawler tracks emitting a first position signalwhich is indicative of the angular orientation of the crawler trackrelative to the associated jacking column; a second angular positiontransducer between the associated swing legs and hinge brackets emittinga second signal which is indicative of the angular orientation of theswing leg relative to the associated hinge bracket; and a processorreceiving the first and second signals and emitting a control signal foractivating the power drive and thereby rotationally moving the crawlertracks relative to the associated jacking columns for keeping thecrawler tracks oriented in the paving direction in response to changesof the first signal caused by pivotal motions of the swing leg about thepivot shaft.
 3. A paving machine according to claim 1 further comprisinga hinge bracket interposed between each swing leg and an associatedsurface of the bolsters and including an upright pivot shaft thatengages the swing leg that permits pivotal movements of the swing legrelative to the hinge bracket about an upright axis in a substantiallyhorizontal plane, the hinge bracket including a pivot connection pointthat is laterally spaced from and fixed in relation to the pivot shaft.4. A paving machine according to claim 1 wherein the power drive is ahelical worm gear drive comprising first and second, diametricallyopposed, helical worm drives engaging and driving a ring gear disposedbetween them.
 5. A paving machine according to claim 2 including afeedback for maintaining an orientation of the crawlers parallel to eachother independently of angular inclinations of the crawlers relative tobolsters.
 6. A paving machine according to claim 5 including a feedbackloop operatively coupled to the bolster swing legs and the crawlertracks for angularly repositioning the crawler tracks relative to therespective swing legs in response to angular motions of the bolsterswing leg about the pivot connection for keeping the crawler tracksoriented in the travel direction.
 7. A paving machine according to claim1, further comprising a holder capable of being held at a fixed length,having a first end pivotally engaging a pivot connection point and asecond end pivotally engaging the swing leg, the holder permittingpivotal motions of the swing leg about a hinge pin and preventingsubstantially any motion of the swing leg when the holder is in itsfixed-length configuration.
 8. A paving machine according to claim 1,further comprising at least one short bolster extension configured tocouple with a trailing module, having a built-in mount connecting andsecuring to at least one rearwardly facing surface of the center module.9. A paving machine according to claim 8, wherein the at least one aftcrawler track and swing leg are configured to freely connect anddisconnect to a side surface of an aft bolster to allow a rear surfaceof the aft bolster to freely connect and disconnect to the trailingmodule.
 10. A paving machine according to claim 9, wherein the at leastone aft crawler track and swing leg are configured to disconnect fromthe side surface of the aft bolster of the paver tractor frame andfurther configured to connect to a an aft end of a reward extendingbolster extension of the trailing module.
 11. A paving machine accordingto claim 1, wherein the at least one aft crawler and swing leg areconfigured to, in combination, disconnect from a transport orientationside of the paver tractor frame and further configured to connect to apaving orientation side of the trailing module.
 12. A paving machineaccording to claim 3, further comprising a hydraulic actuator mounted onthe hinge bracket, permitting the swing leg to pivot relative to thecenter module.
 13. A paving machine according to claim 2, furthercomprising a slew gear drive disposed between the crawler track and thejacking column, configured to receive the control signal and maintainthe crawler tracks in a straight-ahead position.